[IMP] package: disable console clearing

In v15, a collaborative server was introduced.
This server can raise errors (let's say if it cannot start because the port
is already used).

In the current situation, errors are cleared by ts watch mode.
This makes it difficult to see and know what happened.

Part-of: #2202

tsconfig.json

@@ -16,6 +16,7 @@
     "strictNullChecks": true,
     "esModuleInterop": true,
     "allowJs": true,
+    "preserveWatchOutput": true,
     "sourceMap": true
   },
   "include": ["src"],